GAMOPETAL^— COMPOSITE 167 



Pollination. — Cross-pollination is accomplished much as in 

 the Dandelion. The flowers are proterandrous, and the pollen 

 is carried out of the corolla-tube of the disk-flowers by collect- 

 ing-hairs on the unopened style. The hairs, however, are 

 limited to the outer surfaces of the style-branches : and so 

 long as these latter are not separated, the collecting - hairs 

 form a tuft somewhat like a paint-brush. This terminal 

 brush sweeps the pollen upwards. These collecting-hairs are 

 absent from the style of the carpellary ray-flowers, because 

 they are obviously useless to a flower which produces no 

 pollen. The ray-flowers serve to make the inflorescences more 

 conspicuous ; in the Sunflower this is the only service they 

 render to the plant (compare the Guelder-Rose). 



Type V. : CORN-FLOWER {Centaurea cyanus). 



The Corn-flower has no strap-like flowers. Its capitulum 

 is composed solely of tubular flowers. The central flowers, 

 though blue in colour, are very like the disk -flowers of the 

 Daisy, but with a pappus of hairs. The marginal flowers are 

 large, somewhat irregular, and are devoid of stamens, style, 

 stigma, and ovules. Pollination. — -The collecting -hairs are 

 arranged on a globular swelling of the style just beneath the 

 point at which the latter forks. In freshly-opened flowers the 

 filaments of the stamens rapidly contract when the anthers are 

 touched for the first time, and consequently the pollen is 

 suddenly exposed on the collecting hairs. 



GENERAL REMARKS on the Composite. 



In examining the Compositse the chief points to note 

 are — (i.) The inflorescence - receptacle ; its form,; the pres- 

 ence or absence of scale -like bracts amongst the flowers, 

 (ii.) The opening and closing movements of the capit- 

 ulum. (iii.) The calyx and pappus, (iv.) The form of the 

 corolla, (v.) The presence or absence of stamens and carpels 

 in the flowers, (vi.) The occurrence or non-occurrence of an 

 outgrowth of the connective, and of appendages of the anthers, 

 (vii.) The arrangement of the stigma-lines on the arms of the 

 style and the disposition of the collecting-hairs, (viii.) The 

 presence or absence and the form of the pappus on the fruit. 



